Electrode mounts for cold cathode lamps

ABSTRACT

Peripherally welding straight contact pins at the base of the electrodes in a cold cathode lamp provides an electrode mount and lamp structure capable of withstanding and remaining functional when subjected to high vibratory and/or shock conditions. While the preferred electrode mount employs straight contact pins welded to the base of the electrode and passed through a cooperating enveloping glass tube, it has been found that an inexpensive electrode mount can be provided by bending commercially available miniature electron tube contact pin assemblies to peripherally surround the electrode and then welding the contact pins to the base of a hollow electrode. Commercially available glass tubes are then sealed to the contact pin assemblies. While any bending of the supporting contact pins is not desired, the inexpensive electrode mount, although not the most preferred form, is still capable of performing under high vibratory and shock conditions.

United States Patent [1 1 Schoke ELECTRODE MOUNTS FOR COLD CATHODE LAMPS [76] Inventor: James A. Schoke, 4 Cah Dr.,

Westport, Conn. 06880 [22] Filed: Sept. 7, 1971 [21] Appl. No.: 178,209

[52] U.S. Cl. 313/269, 313/292, 313/318, 313/356 [51] Int. Cl. H01j 61/04 [58] Field of Search 313/238, 269, 292, 313/318, 356, 357, 317,109, 209

[56] References Cited UNITED STATES PATENTS 3,201,509 8/1965 Batzle 313/318 X 2,847,605 8/1958 Byer 313/356 X 2,443,632 6/1948 Miller 313/356 X 1,842,525 l/1932 Heintz 313/292 X 2,096,236 10/1937 Freedman 313/292 X Primary Examiner-Paul L. Gensler Attorney-F. Eugene Davis, IV

[ Nov. 13, 1973 57 ABSTRACT Peripherally welding straight contact pins at the base of the electrodes in a cold cathode lamp provides an electrode mount and lamp structure capable of withstanding and remaining functional when subjected to high vibratory and/or shock conditions. While the preferred electrode mount employs straight contact pins welded to the base of the electrode and passed through a cooperating enveloping glass tube, it has been found that an inexpensive electrode mount can be provided by bending commercially available miniature electron tube contact pin assemblies to peripherally surround the electrode and then welding the contact pins to the base of a hollow electrode. Commercially available glass tubes are then sealed to the contact pin assemblies. While any bending of the supporting contact pins is not desired, the inexpensive electrode mount, although not the most preferred form, is still capable of performing under high vibratory and shock conditions.

8 Claims, 5 Drawing Figures PAIENH-Inuuv 13 I915 3772.559

INVENTOR. JAMES A. SCHOKE MATTERN WARE AND DAVIS ATTORNEYS ELECTRODE MOUNTS FOR COLD CATHODE LAMPS BACKGROUND OF THE INVENTION This invention relates to cold cathode lamps, and more particularly to electrode mounts therefor.

With the development of cold cathode lamps and their inherent advantages in various circumstances over the incandescent type lamps, cold cathode lamps are subjected to performing under various undesirable conditions. In most of the prior art lamps, the cathode of the lamp is supported by one or two wires which pass through the enveloping glass tube, supportingly contacting the electrode at merely one ot two points. Also, U-shaped and I-I-shaped supporting wires have been developed, but are equally ineffective since the cathode is merely supported in a single plane. These various electrode mounts are not capable of withstanding high vibration or shock loads and, under these conditions, will fatigue and break.

With the advent of new, more sophisticated air transportation equipment, the need for cold cathode fluorescent lamps which are capable of withstanding the vibration and shock conditions of air transportation has become necessary. The simple wire suport at the base of the cathode or the single plane cathode holding assemblies were not capable of satisfying these more demanding requirements, particularly when the lamp tubes are bent into offset U or G or other desirable configurations. Although these configurations are desirable for the lighting requirements in the air transports, they do impart each particular lamp with a center of gravity offset from its terminating ends, which greatly increases the bending moments at the lamp ends. This offset center of gravity and its resulting bending moment increase substantially the requirement for lamps having electrode mounts that can withstand these high vibration and shock conditions.

OBJECTS OF THE INVENTION It is a principal object of this invention to provide an electrode mount for cold cathode fluorescent lamps capable of withstanding high vibratory conditions.

Another object of this invention is to provide an electrode mount of the above character capable of withstanding high shock conditions.

Another object of this invention is to provide an electrode mount of the above character which is inexpen sive to manufacture.

A further object of this invention is to provide an electrode mount of the above character which is simple to install and capable of being manufactured from commercially available products.

Another object of this invention is to provide an electrode mount of the above character which is capable of withstanding the bending moments caused by various shaped lamp configurations which impart the lamp with a center of gravity that is offset from the lamps ends.

Other and more specific objects will be apparent from the features, elements, combinations and operating proceduresdisclosed in the following detailed description and shown in the drawings.

SUMMARYOF THE INVENTION tact pins being secured in an enveloping glass tube. It has been found that straight, short contact pins provide the best shock absorption and endure the greatest vibration. Furthermore, the efficacy of the electrode mount is substantially increased if the mounting pins peripherally surround the electrode at equal spacings from each other. Although the preferred embodiment of the electrode mount of this invention is a substantial improvement over the commercially available cold cathode tube mounts, the high cost of manufacturing this preferred embodiment renders the cold cathode tube with the electrode mount of the invention generally salable for very special stringent requirements. However, it has been found that with a slight reduction in performance, an inexpensive, very competitive cold cathode lamp can be manufactured. This inexpensive cathode lamp employs commercially available electrodes, commercially available glass tubes, and commercially available miniature electron tube contact pin assemblies, or button stems. The pins of the assembly are bent to the shape of the electrode and are individually welded at the base of the electrode. Welded electrode pin assemblies are then sealed at both ends of the glass tube. Once the tube has been filled with the desired gas and sealed, the cold cathode lamp is ready for use.

Preferably, end caps are secured to the exposed pins at both ends of the cold cathode lamp to provide easier installation and removal, while also providing greater shock and vibration resistance.

The invention accordingly comprises the features of construction, combinations of elements, and arrangement of parts which will be exemplified in the constructions hereinafter set forth, and the scope of the invention will be indicated in the claims.

THE DRAWINGS For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings, in which:

FIG. 1 is a perspective view partially broken away of the cold cathode lamp of this invention;

FIG. 2 is an exploded side view partially in cross section showing one end of the cold cathode lamp of FIG.

FIG. 3 is a cross-sectional top view taken along the line 3-3 of FIG. 2;

FIG. 4 is a perspective view showing the preferred electrode mount construction; and

FIG. 5 is a top plan view showing a G-shaped lamp configuration.

DETAILED DESCRIPTION One embodiment of cold cathode fluorescent lamp 20 is presented in FIG. 1. Lamp 20 comprises enveloping glass bulb 22 and electrode mount assembly 24. Glass bulb 22 provides the outer enveloping surface of cold cathode lamp 20 and may be of any desired length, diameter, and shape. The inner surface of glass tube 22 is covered or coated with a composition containing finely divided luminescent or fluorescent material. As is well known in the art, this coating composition is generally baked onto the interior surface of glass tube 22 and activated by the ultraviolet light produced from the gas discharge occurring between electrodes to provide the desired light intensity.

Electrode mount assembly 24 comprises a tubular electrode 26, a supporting contact pin assembly 28, and an end cap 30. End cap 30 is incorporated to render lamp readily installable while also providing a positive firm interconnection between lamp 20 and its housing contacts.

Supporting contact pin assembly 28 can best be seen in FIGS. 2 and 3. Assembly 28 incorporates contact pins 32, supportingly held by glass base 34. In order to construct an inexpensive lamp 20 employing the electrode mount of this invention, commercially available miniature contact pin assemblies are employed, along with commercially available glass bulbs.

One form of commercially available button stems or contact pin assemblies 28 incorporates seven contact pins 32 which are sealed in glass base 34 so as to provide a substantially circular array of contact pins at both ends. Assemblies 28 may or may not incorporate an exhaust tube. Since the preferred pin assembly has the diameter of the circular array of pins, contact pins 32 must be bent to provide a wider circular array less than the diameter of tubular electrode in order to peripherally mount contact pins 32 to the base of tubular electrode 26. Then the contact pins are connected to electrode 26 at its base with weld 36.

Preferably, each contact pin 32 is individually welded to electrode 26 at a single contact point substantially about the electrode periphery where the convex base 38 of electrode 26 blends into the substantially cylindrical portion 40 of electrode 26. A single weld point for each pin 32 on the periphery of electrode 26 is preferred in order to minimize distortion of the pins. This is desirable, since any change in the pin structure will change its resonant frequency.

Pin assembly 28 with electrode 26 supportingly welded in place is inserted, electrode first, through both ends of glass tube 22. Since base 34 of pin assembly 28 is substantially the same diameter as the open end of tube 22, the contact area between base 34 and bulb 22 is thoroughly heated to provide fusion of one with the other. This results in the creation of a sealed glass bulb with a gas filling port 42, extending from one of the glass bases 34, being the only access to the interior of glass bulb 22.

Assembly of fluorescent lamp 20 is then completed by evacuation and filling of bulb 22 with the desired gas through port 42 during the well known lamp processing procedure, followed by the sealing of port 42. End cap 30 is then positioned on the portion of pins 32 extending out from glass base 34 and mechanically and electrically connected thereto. Once caps 30 have been secured to both sets of exposed pins, the construction of fluorescent lamp 20 is completed, and after cleaning and treatment of the lamp surface for either high or low resistance, as is known in the art, the lamp is ready for installation and operation under high vibratory and shock conditions.

The preferred embodiment of the electrode mount of this invention is shown in FIG. 4. Eight pins 50 peripherally surround electrode 26 and are welded thereto at their terminating ends at equal distances from each other. Pins 50 are preferably short in length and are welded at a single point on the outer periphery of electrode 26 where convex base 38 of electrode 26 blends into cylindrical portion 40 of electrode 26. Pins 50 are sealed in glass base 52, which is used, as described above, to seal the ends of the enveloping tube. Al-

though eight pins are shown, any number of pins peripherally mounted in a circle and equally spaced apart can be used with equal efficacy.

Short, substantially straight pins are preferred in constructing the electrode of this invention, since any bend in the wire pins lowers the resonant frequency of the electrode, thereby changing the beam produced. Since a higher resonant frequency is preferred, the substantially straight pins 50 are more desirable, with a short distance between convex base 38 and glass base 52. Although electrode 26 as depicted herein is substantially cylindrical in shape, cylindrical electrodes are not required and any particular electrode shape can be successfully employed with the electrode mount of this invention.

One commercial application for the electrode mount of this invention is shown in FIG. 5. In various air transport vehicles, pairs of substantially G-shaped lamps are required. Because of the irregular shape of lamp 55, its center of gravity is offset from its terminating ends 56. This center of gravity location is believed to substantially increase the bending moments about ends 56, thereby also substantially increasing the shock and vibration at these points.

Since the electrode mount of this invention has been designed with these requirements in mind, the electrode mount is able to efficiently and continuously perform under these severe conditions with any vibration or shock induced failures.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language might be said to fall therebetween.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

l. A discharge lamp comprising:

A. an elongated glass tube substantially circular in cross section throughout its length;

B. two substantially cylindrical hollow electrodes incorporating convex bases, each axially aligned with and centered in an end of said glass tube;

C. a first electron control tube stem comprising a. a substantially circular pin-supporting first base axially aligned with, centered in, and integrally secured at its peripheral edge to one end of said glass tube, and b. seven circularly arrayed electrode supporting pins axially aligned with and centered in an end of said glass tube 1. integrally secured substantially about their mid-points to said first supporting base in a substantially circular array axially aligned with and centered in an end of said glass tube, 2. at least all but one pair of said pins being equally spaced in said circular array, 3. extending from said supporting base both into said glass tube and away from said glass tube, and

4. said pins extending into said glass tube being welded to the base of one of said electrodes in a substantially circular array;

D. a second electron control tube stem comprising a. a substantially circular pin-supporting second base axially aligned with, centered in, and integrally secured at its peripheral edge to one end of said glass tube,

b. seven circularly arrayed electrode supporting pins axially aligned with and centered in one end of said glass tube 1; integrally secured substantially about their mid-points to said second supporting base in a substantially circular array axially aligned with and centered in one end of said glass tube,

2. at least all but one pair of said pins being equally spaced in said circular array,

3. extending from said supporting base both into said glass tube and away from said glass tube, and

4. said pins extending into said glass tube being welded to the base of one of said electrodes in a substantially circular array;

c. an air-evacuation tube extending from the center of said second supporting base; and

E. two fixture mounting end caps each of which are bonded in electrical conductive relationship to said pins extending away from said supporting base and said glass tube, said end caps being metal circular cylinders closed at their outer ends.

2. A discharge lamp as defined in claim 1, wherein said pins are substantially straight and welded at their terminating ends to their respective electrode.

3. A discharge lamp as defined in claim 1, wherein said pins are peripherally mounted to said electrode substantially about the plane where said convex base blends into said cylindrical portion.

4. A discharge lamp as defined in claim 3 having an additional eighth pin, wherein all of said pins are secured at equal arcuate distances from each other.

5. A discharge lamp as defined in claim 3, wherein the pins are bendingly adjusted to peripherally surround the electrode for welding thereto.

6. A discharge lamp as defined in claim 3, wherein the arcuate distance between any two adjacent pins but one pair of adjacent pins is equal to the quotient obtained by dividing 360 by one more than the total number of pins.

7. A discharge lamp as defined in claim 1, wherein the lamp comprises a center of gravity that is offset from the terminating ends of said tube.

8. A discharge lamp as defined in claim 7, wherein said glass tube comprises a substantially G shape. 

1. A discharge lamp comprising: A. an elongated glass tube substantially circular in cross section throughout its length; B. two substantially cylindrical hollow electrodes incorporating convex bases, each axially aligned with and centered in an end of said glass tube; C. a first electron control tube stem comprising a. a substantially circular pin-supporting first base axially aligned with, centered in, and integrally secured at its peripheral edge to one end of said glass tube, and b. seven circularly arrayed electrode supporting pins axially aligned with and centered in an end of said glass tube
 1. integrally secured substantially about their mid-points to said first supporting base in a substantially circular array axially aligned with and centered in an end of said glass tube,
 2. at least all but one pair of said pins being equally spaced in said circular array,
 3. extending from said supporting base both into said glass tube and away from said glass tube, and
 4. said pins extending into said glass tube being welded to the base of one of said electrodes in a substantially circular array; D. a second electron control tube stem comprising a. a substantially circular pin-supporting second base axially aligned with, centered in, and integrally secured at its peripheral edge to one end of said glass tube, b. seven circularly arrayed electrode supporting pins axially aligned with and centered in one end of said glass tube
 1. integrally secured substantially about their mid-points to said second supporting base in a substantially circular array axially aligned with and centered in one end of said glass tube,
 2. at least all but one pair of said pins being equally spaced in said circular array,
 3. extending from said supporting base both into said glass tube and away from said glass tube, and
 4. said pins extending into said glass tube being welded to the base of one of said electrodes in a substantially circular array; c. an air-evacuation tube extending from the center of said second supporting base; and E. two fixture mounting end caps each of which are bonded in electrical conductive relationship to said pins extending away from said supporting base and said glass tube, said end caps being metal circular cylinders closed at their outer ends.
 2. at least all but one pair of said pins being equally spaced in said circular array,
 2. at least all but one pair of said pins being equally spaced in said circular array,
 2. A dischargE lamp as defined in claim 1, wherein said pins are substantially straight and welded at their terminating ends to their respective electrode.
 3. A discharge lamp as defined in claim 1, wherein said pins are peripherally mounted to said electrode substantially about the plane where said convex base blends into said cylindrical portion.
 3. extending from said supporting base both into said glass tube and away from said glass tube, and
 3. extending from said supporting base both into said glass tube and away from said glass tube, and
 4. said pins extending into said glass tube being welded to the base of one of said electrodes in a substantially circular array; D. a second electron control tube stem comprising a. a substantially circular pin-supporting second base axially aligned with, centered in, and integrally secured at its peripheral edge to one end of said glass tube, b. seven circularly arrayed electrode supporting pins axially aligned with and centered in one end of said glass tube
 4. A discharge lamp as defined in claim 3 having an additional eighth pin, wherein all of said pins are secured at equal arcuate distances from each other.
 4. said pins extending into said glass tube being welded to the base of one of said electrodes in a substantially circular array; c. an air-evacuation tube extending from the center of said second supporting base; and E. two fixture mounting end caps each of which are bonded in electrical conductive relationship to said pins extending away from said supporting base and said glass tube, said end caps being metal circular cylinders closed at their outer ends.
 5. A discharge lamp as defined in claim 3, wherein the pins are bendingly adjusted to peripherally surround the electrode for welding thereto.
 6. A discharge lamp as defined in claim 3, wherein the arcuate distance between any two adjacent pins but one pair of adjacent pins is equal to the quotient obtained by dividing 360* by one more than the total number of pins.
 7. A discharge lamp as defined in claim 1, wherein the lamp comprises a center of gravity that is offset from the terminating ends of said tube.
 8. A discharge lamp as defined in claim 7, wherein said glass tube comprises a substantially G shape. 